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Worldwide Shortage of Barium
New submitter redhat_redneck writes "The U.S. and Canada has been experiencing a shortage of barium sulfate, which is used as contrast for upper and lower GI studies. It has reached the point where doctors are being asked not to order these exams except in emergencies, and some exams are being cancelled. Here's the letter that's been put out by the manufacturer. The longer this drags on, the more serious this issue becomes, eventually impacting patients and healthcare providers in both cost and quality of care. Some sources point to a dramatic drop in Chinese production. In their defense, it seems China is changing safety regulations. Medical use only make a fraction of the uses of barium sulfate, but it's going to be disproportionately affected by this shortage. We can't go back to our old contrast Thorotrast; it causes cancer. Does anyone know of alternatives to barium?"
Of course Slashdot readers are supposed to get it.
Contrast is what it says. It's there to make whatever you want investigate stand out from the rest observe it. For instance to make blood vessels easier to see. (Now I don't know whatever this is x-ray, MR, ultra-sound or whatever.) My english isn't good enough to know what GI is (gut-ingestion?) but I guess it's the stuff from the throat to the ass.
what GI is (gut-ingestion?) but I guess it's the stuff from the throat to the ass.
Gastrointestinal, your guess is correct: mouth-esophagus-stomach-intestines-anus. It's basically one continuous external surface inside the body.
Gastro-Intestinal aka the bit between the mouth and the anus. This stuff shows up (contrasts) on x-rays. Upper studies involve drinking it. Lower studies involve insertion from the other end. In other words, it's used for testing gut disorders and if you aren't swallowing it, you can shove it up your arse.
Barium is a rare earth metal.
Not exactly, Barium is an alkaline earth metal, related to Magnesium and Calcium. Interestingly though, the U.S. are one of the largest producers of Barium, accounting for about 8% of the world wide barium output. It's mainly mined as barit, or heavy spar.
Layman's explanation: Contrast agent is something that shows up as a bright color on your scan. There are many different kinds of contrast used for many different purposes, too many to list here. Barium contrast is swallowed and shows up as bright white on regular X-rays and CT scans (CTs are a multitude of X-rays taken by a computerized scanner which is then turned into a quasi-3D representation.) The reason somebody would use barium is to look at the shape of the esophagus (food pipe), stomach, intestines, and rectum to see if there are any parts that are too wide, too narrow/pinched off, the wrong shape, if there is a blockage, etc.
Not so layman's explanation of the tests mentioned:
- Barium swallow: Barium is swallowed and a real-time series of X-rays (fluoroscopy) of the throat (pharynx) is done to see if the barium is swallowed properly. The resulting video shows where the barium goes. This is ordered if the doctor suspects the person may be having problems swallowing (aspiration or refluxing.)
- Esophogram: Barium is swallowed and fluoroscopy of the esophagus is performed to see if there are any abnormalities of the size/shape/anatomy of the esophagus. This is also ordered if somebody has trouble swallowing and the doctor suspects some problem like a stricture, widening of the esophagus (achalasia), abnormal anatomy of the esophagus (such as a diverticulum, malignancy, etc.)
- UGI = Upper gastrointestinal study. This fluoroscopy stufy follows the barium from being swallowed until it goes into the stomach. It shows all of the same things as the esophagram along with the size/shape/anatomy of the stomach as well. Ordered for the same reasons as the esophagram as well as if you suspect some anatomic problem with the stomach (e.g. stomach stapling/bypass not working correctly, etc.)
- Small bowel follow through: Barium is swallowed and then a series of individual X-rays taken at certain time intervals to track the progress of the barium through the stomach and small intestine. This is done to investigate things like the stomach emptying too slowly and obstructions in the small intestine.
- Barium enema: Barium is given via enema into the rectum to look at the anatomy of the rectum. This can investigate anatomic abnormalities of the rectum such as masses and fistulas (a hole from the rectum to somewhere else, this is abnormal.) This can also be used to both diagnose and treat intusussception (a disease of infants where part of the large intestine telescopes into itself.)
Just "gittin-r-done," day after day.
Typical impurities in US barium sulfate (Nevada mines) are silica and strontium sulfate. Silica can be somewhat removed via froth flotation using standard commercially known techniques. The Sr is bound up in the Ba-Sr-SO4 lattice and very difficult to remove. Were they not bound together in the crystalline structure you could likely use an alkaline leach with sodium hydroxide (I saw a patent from the 1930s or 1940s that discussed this very approach), but when they are bound together you do not get selective leaching. Also, because they are bound together gravimetric separation (SrSO4 = ~3.8 SG IIRC, BaSO4 = ~4.45 SG) doesn't work.
Sr and Ba are very similar chemically, but to meet the USP requirement of 97.5% min BaSO4 you have to be able to get the purity up (or start with a high purity ore). The USP assay test differentiates between the two because of the difference in solubility as chromates - the Sr chromate is much more soluble but you have to convert everything to chromates to get the Sr to drop out, then you'd have to convert the Ba chromate back to BaSO4 and not leave any chromate in there, as it is very toxic. At that point you are no longer dealing with natural purified barium sulfate but are instead making a precipitated barium sulfate, in which case you could just start with pretty much any barium compound and fully react it with sulfuric acid. The problem here is that any soluble barium left behind is very toxic (for a real life example of what could go wrong see http://en.wikipedia.org/wiki/Celobar_incident).
By the time you do all of the processing above the cost is nowhere near what could be achieved with natural, high-purity barium sulfate ore that undergoes a simple acid leach.